Profile control in enhanced oil recovery
AssigneeShell Oil Company
InventorsLee N. Morgenthaler, William H. Korcz, John L. Greak, James R. Erickson
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Abstract
Oil recovery method using polymer solutions in which highly permeable strata are made significantly less permeable while less permeable strata are not made significantly less permeable. This is accomplished by heating more permeable strata by injection of hot fluids, and then injection of a crosslinkable vinyl aromatic-conjugated diolefin polymer and a temperature activated crosslinking agent. A crosslinked gel is formed in the initially more permeable strata, permitting recovery of oil from the initially less permeable strata.
Claims17
A process to reduce permeability in highly permeable strata of a permeable subterranean formation having at least one highly permeable stratum and at least one less permeable stratum comprising the steps of:
- a) injecting a heat medium into the formation thereby increasing the temperature of at least a portion of the highly permeable strata to above a crosslinking temperature and not increasing the temperature of the less permeable strata to above the crosslinking temperature;
- b) injecting into the formation a polymer solution comprising a continuous hydrocarbon phase, a block copolymer comprising at least one conjugated diolefin block containing ethylenic unsaturation and at least one vinyl aromatic block and having a glass transition temperature which is greater than the temperature of the less permeable strata and less than the crosslinking temperature, and a free radical crosslinking agent wherein the free radical crosslinking agent is capable of crosslinking the block copolymer at the crosslinking temperature in a quarter of an hour to 72 hours and crosslinks the block copolymer at the temperature of the less permeable strata at a rate of one tenth or less of the rate at crosslinking temperatures;
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- c) crosslinking at least a portion of the polymer within the highly permeable strata and thereby reducing the permeability of the highly permeable strata.
Dependencies are inferred from the claim text.